U.S. patent number 7,197,890 [Application Number 10/938,165] was granted by the patent office on 2007-04-03 for valve for preventing unpowered reverse run at shutdown.
This patent grant is currently assigned to Carrier Corporation. Invention is credited to Thomas J. Dobmeier, Alexander Lifson, Michael F. Taras.
United States Patent |
7,197,890 |
Taras , et al. |
April 3, 2007 |
Valve for preventing unpowered reverse run at shutdown
Abstract
An inventive method of preventing unpowered reverse rotation in
a compressor includes the steps of placing a solenoid valve at a
location near compressor discharge. The valve is preferably
actuated soon after the power to the motor is cut off, blocking the
flow of refrigerant from expanding back toward the compression
chambers of the compressor. The compressor is disclosed as a scroll
compressor, but may also be a screw compressor. These two types of
compressors are susceptible to undesirable unpowered reverse
rotation when compressed refrigerant re-expands through the
compression elements from the compressor discharge into the
compressor suction. By blocking the flow of refrigerant, this
unpowered reverse rotation is prevented. A high pressure switch can
be positioned directly upstream of the solenoid valve to
immediately stop the compressor if the valve malfunctions and
blocks the flow of refrigerant during normal compressor operation.
This high pressure switch will prevent the continued operation of
the compressor with the blocked discharge line by sending a signal
to a control to cut the power to the compressor motor. A pressure
differential switch can be utilized in a similar manner to avoid
undesirably high pressure differentials across the valve. Also, the
valve itself may be equipped with the flow bypass that opens when
pressure differential across the valve exceeds a safe limit.
Inventors: |
Taras; Michael F.
(Fayetteville, NY), Lifson; Alexander (Manlius, NY),
Dobmeier; Thomas J. (Phoenix, NY) |
Assignee: |
Carrier Corporation (Syracuse,
NY)
|
Family
ID: |
36034169 |
Appl.
No.: |
10/938,165 |
Filed: |
September 10, 2004 |
Prior Publication Data
|
|
|
|
Document
Identifier |
Publication Date |
|
US 20060056989 A1 |
Mar 16, 2006 |
|
Current U.S.
Class: |
62/217; 62/228.3;
417/279 |
Current CPC
Class: |
F04C
28/28 (20130101); F04C 28/06 (20130101); F04C
29/042 (20130101); F04C 23/008 (20130101); F04C
18/0215 (20130101); F04C 2270/72 (20130101) |
Current International
Class: |
F25B
41/04 (20060101); F25B 1/00 (20060101); F25B
49/00 (20060101) |
Field of
Search: |
;62/228.1,228.3,217
;417/279,291,310 ;418/55.1 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Norman; Marc
Attorney, Agent or Firm: Carlson Gaskey & Olds
Claims
What is claimed is:
1. A compressor comprising: a compressor housing and a compressor
pump unit; a motor for driving said compressor pump unit; said
compressor pump unit being of the sort that is susceptible to
unpowered reverse rotation, said compressor pump unit having
compression chambers for compressing a refrigerant, and delivering
the compressed refrigerant into a discharge chamber; a powered
shut-off valve for blocking flow of refrigerant at a location
between said discharge chamber and a downstream heat exchanger,
such that refrigerant cannot flow from the downstream heat
exchanger into said discharge chamber when said power shut-off
valve is in a closed position.
2. The compressor as set forth in claim 1, wherein said compressor
pump unit is a scroll compressor pump unit.
3. The compressor as set forth in claim 1, wherein said compressor
pump unit is a screw compressor pump unit.
4. The compressor as set forth in claim 1, wherein said powered
shut-off valve is located on a compressor discharge tube.
5. The compressor as set forth in claim 1, wherein said powered
shut-off valve is located on a compressor discharge line.
6. The compressor as set forth in claim 1, wherein a control for
controlling said powered shut-off valve actuates said powered
shut-off valve in a preset period of time, after said motor is
stopped.
7. The compressor as set forth in claim 6, wherein said powered
shut-off valve is actuated by said control in more than 0.1 second
after power to said motor is cut off.
8. The compressor as set forth in claim 6, wherein said control
actuates said powered shut-off valve between 0.1 and 1.0 second
after power to said motor is cut off.
9. The compressor as set forth in claim 1, wherein a pressure
switch is positioned upstream of said powered shut-off valve, said
pressure switch communicating with a control for said electric
motor, said pressure switch being operable to identify an
undesirably high pressure upstream of said powered shut-off valve,
and stop operation of said motor should an undesirably high
pressure be sensed.
10. The compressor as set forth in claim 1, wherein said powered
shut-off valve is a solenoid powered valve.
11. The compressor as set forth in claim 1, wherein said powered
shut-off valve will open from its closed position if pressure
exceeds a safe pressure.
12. The compressor as set forth in claim 1, wherein said powered
shut-off valve is a normally open valve.
13. The compressor as set forth in claim 1, wherein a pressure
differential switch is positioned to sense a pressure differential
across said powered shut-off valve, said pressure differential
switch communicating with a control for said powered shut-off
valve, said pressure differential switch being operable to identify
an undesirably high pressure differential across said powered
shut-off valve, and stop operation of said motor should an
undesirably high pressure differential be sensed.
14. The compressor as set forth in claim 1, wherein said powered
shut-off valve will open from its closed position if a pressure
differential exceeds a safe pressure differential.
15. The compressor as set forth in claim 1, wherein said powered
shut-off valve is a valve equipped with a flow bypass that is
opened when a pressure differential across the valve exceeds a safe
pressure differential.
16. The compressor as set forth in claim 1, wherein said compressor
pump unit delivering a compressed refrigerant through a discharge
port and into the discharge chamber, refrigerant flowing from the
discharge chamber passing through a discharge tube leaving the
compressor housing, and said power shut-off valve being positioned
in the discharge tube.
17. A refrigerant cycle comprising: a compressor, said compressor
being of the sort that is susceptible to unpowered reverse
rotation, said compressor having compression chambers for
compressing a refrigerant, and delivering the compressed
refrigerant into a discharge chamber; a heat exchanger positioned
downstream of said compressor, refrigerant from said discharge
chamber passing to said downstream heat exchanger; and a powered
shut-off valve for blocking flow of refrigerant at a location
between said discharge chamber and the downstream heat exchanger,
such that refrigerant cannot flow from the downstream heat
exchanger into said discharge chamber when said power shut-off
valve is in a closed position.
18. The refrigerant cycle as set forth in claim 17, wherein said
compressor pump unit is a scroll compressor pump unit.
19. The refrigerant cycle as set forth in claim 17, wherein said
compressor pump unit is a screw compressor pump unit.
20. The refrigerant cycle as set forth in claim 17, wherein said
powered shut-off valve is located on a compressor discharge
tube.
21. The refrigerant cycle as set forth in claim 17, wherein said
powered shut-off valve is located on a compressor discharge
line.
22. The refrigerant cycle as set forth in claim 17, wherein a
control for controlling said powered shut-off valve actuates said
powered shut-off valve in a preset period of time, after said motor
is stopped.
23. The refrigerant cycle as set forth in claim 22, wherein said
powered shut-off valve is actuated by said control more than 0.1
second after power to said motor is cut off.
24. The refrigerant cycle as set forth in claim 22, wherein said
control actuates said powered shut-off valve between 0.1 and 1.0
second after power to said motor is cut off.
25. The refrigerant cycle as set forth in claim 17, wherein a
pressure switch is positioned upstream of said powered shut-off
valve, said pressure switch communicating with a control for said
electric motor, said pressure switch being operable to identify an
undesirably high pressure upstream of said powered shut-off valve,
and stop operation of said motor should an undesirably high
pressure be sensed.
26. The refrigerant cycle as set forth in claim 17, wherein said
powered shut-off valve is a solenoid powered valve.
27. The refrigerant cycle as set forth in claim 17, wherein said
powered shut-off valve will open from its closed position if
pressure exceeds a safe pressure.
28. The refrigerant cycle as set forth in claim 17, wherein said
powered shut-off valve is a normally open valve.
29. The refrigerant cycle as set forth in claim 17, wherein a
pressure differential switch is positioned to sense a pressure
differential across said powered shut-off valve, said pressure
differential switch communicating with a control for said powered
shut-off valve, said pressure differential switch being operable to
identify an undesirably high pressure differential across said
powered shut-off valve, and stop operation of said motor should an
undesirably high pressure differential be sensed.
30. The refrigerant cycle as set forth in claim 17, wherein said
powered shut-off valve will open from its closed position if a
pressure differential exceeds a safe pressure differential.
31. The refrigerant cycle as set forth in claim 17, wherein said
powered shut-off valve is a valve equipped with a flow bypass that
is opened when a pressure differential across the valve exceeds a
safe pressure differential.
32. The refrigerant cycle as set forth in claim 17, where the
refrigerant cycle is an air conditioning cycle.
33. The refrigerant cycle as set forth in claim 17, where the
refrigerant cycle is a heat pump cycle.
34. The refrigerant cycle as set forth in claim 17, where the
refrigerant cycle includes an economizer branch.
35. The refrigerant cycle as set forth in claim 17, wherein said
compressor pump unit delivering a compressed refrigerant through a
discharge port and into the discharge chamber, refrigerant flowing
from the discharge chamber passing through a discharge tube leaving
the compressor housing, and said power shut-off valve being
positioned in the discharge tube.
36. A method of controlling a compressor comprising the steps of:
(1) compressing a refrigerant within a compressor pump unit, of the
sort that is susceptible to unpowered reverse rotation; (2) cutting
power to a motor for driving said compressor pump unit; and (3)
blocking flow of a compressed refrigerant from being expanded
through compressor pump unit by actuating a powered valve, said
flow of compressed refrigerant being blocked at a location
downstream of a discharge chamber which receives the compressed
refrigerant from the compressor pump unit.
Description
BACKGROUND OF THE INVENTION
This application relates to a valve located adjacent to a
compressor discharge line, and operable to prevent backflow of
compressed refrigerant into a compressor pump unit, and the
resultant reverse run of the compressor upon a compressor
shutdown.
Compressors are utilized in most refrigerant compression
applications. In a compressor, a refrigerant is typically brought
into a suction chamber that surrounds a motor for a compressor pump
unit. The suction refrigerant cools the motor, and eventually
travels into the compression chambers of the compressor pump unit
where it is compressed, and passes through a discharge port into a
discharge chamber. From the discharge chamber, the refrigerant
passes into a compressor discharge tube, and then downstream to the
next component in the refrigerant system.
One common type of compressors that is becoming widely utilized is
a scroll compressor. In a scroll compressor, a first scroll member
has a base and a generally spiral wrap extending from the base, and
a second scroll member has a base and a generally spiral wrap
extending from its base. The two wraps interfit to define the
compression chambers. The first scroll member is caused to orbit
relative to the second scroll member, and as the two orbit relative
to each other, the size of the compression chambers decreases, thus
compressing the entrapped refrigerant.
Scroll compressors have a problem with an issue called unpowered
reverse rotation. The scroll compressor is preferably driven to
orbit in a preferred direction. If the first scroll member is
caused to orbit in the opposed direction, undesirable noise and
potential damage to the compressor may occur, due to over-speeding
of the orbiting scroll and shaft counterweights.
At shutdown of the scroll compressor, there is a significant amount
of compressed refrigerant stored in the condenser and adjacent
discharge piping downstream of the compressor. Upon a shutdown,
this compressed refrigerant expands through the compression
chambers, and drives the orbiting scroll member in the reverse
direction. This is undesirable.
Discharge check valves installed inside of the scroll compressor
are sometimes utilized to block the refrigerant from expanding
through the scroll elements and thus preventing the reverse
rotation. The check valves may have reliability problems as they
can wear and break in fatigue after prolonged operation. As such,
there is a concern with regard to unpowered reverse rotation as it
relates to the use of the internal check valves.
A similar problem exists with screw compressors where the
refrigerant can expand through the screw compression elements, if
there is no adequate means to block this reverse flow of
refrigerant. The rotation of screw elements in reverse can damage
the screw rotors of the screw compressor.
SUMMARY OF THE INVENTION
In a disclosed embodiment of this invention, a solenoid valve is
placed in the discharge tube or into the discharge line adjacent to
the compressor outwardly of the compressor housing. Preferably, the
valve is closed shortly after a shutdown of the compressor motor.
If the valve shuts closed before or immediately at shutdown of the
motor, there is a potential problem with an increase in the
pressure of refrigerant, since the motor will continue to run in a
forward direction for a short period of time after the shutdown.
However, if the valve shuts closed after a significant amount of
time has expired after the motor shutdown, then the refrigerant
from the condenser and discharge line will be able to re-expand
back through the scroll elements causing them to run in reverse.
Thus it is imperative to close the valve within a short time window
for optimum performance. Thus, in a disclosed embodiment,
preferably, the valve is closed between 0.1 second and 1.0 second
after the shutdown of the motor. A solenoid valve is disclosed, but
other valve types come within the scope of this invention.
In another feature, a high pressure switch is positioned upstream
of the solenoid valve. If the solenoid valve should inadvertently
close while the compressor is running, the high pressure switch
will quickly sense an undesirable increase in pressure. The high
pressure switch is preferably wired to a control, which can stop
the motor, should an over-pressure situation be detected.
These and other features of the present invention can be best
understood from the following specification and drawings, the
following of which is a brief description.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a schematic view of a refrigerant cycle incorporating the
present invention.
FIG. 2 shows optional features.
FIG. 3 shows further optional features.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
A compressor 20 is illustrated in FIG. 1 having a compressor pump
unit 22. A suction tube 24 delivers a suction refrigerant into a
suction plenum 25. From the suction plenum 25, the refrigerant can
pass upwardly into compression chambers 27 formed between an
orbiting scroll member 30 and a non-orbiting scroll member 32. It
is known that for a compressor pump unit 22, which utilizes scroll
members, there is a problem with unpowered reverse rotation at a
shutdown, as described above. While a scroll compressor is
illustrated, any type of compressor that has a potential problem
with unpowered reverse rotation (a screw compressor, for example)
may benefit from this invention.
A discharge chamber 34 is shown directly downstream of a fixed
scroll 32. As shown in the drawing, there is no check valve
separating the discharge chamber 34 and the refrigerant exit from
the fixed scroll port 36. The function of the check valve in this
case is substituted by a valve member 40. As shown, from the
chamber 34, refrigerant can pass through a discharge tube 38, and
downstream towards a condenser 48, a main expansion device 50, and
an evaporator 52.
While the invention is shown illustrated in a compressor 20 with
the condenser 48 directly downstream, it should be understood that
the inventive compressor can also be utilized in a refrigerant
cycle incorporating the ability to select routing of the
refrigerant from the discharge tube 38 either to the condenser 48,
or to the evaporator 52. Such selective routing can be
accomplished, for example, by using a four-way reversing valve 122
(see FIG. 2). Such refrigerant cycles are utilized in heat pump
systems, and are known to a worker of ordinary skill in this art.
Also the refrigerant system can additionally be equipped with vapor
injection, liquid injection or by-pass unloading capabilities (see
FIG. 3) as known in the art.
A motor 37 drives a shaft 39 to cause the orbiting scroll member 30
to orbit relative to the non-orbiting scroll member 32. Although
the non-orbiting scroll member 30 is shown as a fixed scroll, this
invention also extends to scroll compressors wherein the
non-orbiting scroll can move axially.
The invention disclosed in this application relates to a valve
member 40 that is operable by a solenoid valve control 44 to block
a reverse flow of refrigerant from the condenser 48 through the
tube 38 upon the compressor shutdown. Once again, other types of
shut-off valves can be used as well.
As shown, a control 46 communicates with the valve control 44, and
also with a shut-off switch 47 (positioned either inside or outside
the compressor) for the motor 37. Further, an optional high
pressure switch 42 senses the pressure in the tube 38 and
communicates with the control 46.
When the control 46 causes the motor 37 to stop, it actuates the
solenoid valve control 44 to drive the valve 40 to the closed
position such as illustrated in FIG. 1. Prior to this actuation,
the valve 40 is in a retracted position at which it does not block
flow through the discharge tube 38. For safety consideration it is
preferred to use a type of a valve that will maintain a normally
open position after the power to this valve is cut off.
Preferably, this actuation occurs in a short period of time after
the signal has been sent to stop the motor 37. This allows the
motor to stop forward rotation, and prevent further compression,
before the valve 40 precludes a flow of the compressed refrigerant.
On the other hand, it is desirable that the valve 40 be moved to
block the flow some time quite soon after the shutdown to prevent a
reverse flow of refrigerant back through the tube 38 from the
downstream locations, and potentially cause an unpowered reverse
run situation. In a disclosed embodiment, this period of time is
between 0.1 and 1.0 seconds. Of course, other time periods would be
within the scope of this invention.
Further, since it is possible that the valve control 44 could
malfunction and drive the valve 40 to its closed position, when the
compressor is operating, high pressure switch 42 is utilized.
Should high pressure switch 42 sense that the pressure in the tube
38 is higher than is expected or desirable, it may send a signal to
the control 46. Control 46 is then operable to stop the motor 37
such that the malfunction can be evaluated. It is also within the
scope of this invention to utilize a solenoid valve that will be
forced to open if the pressure difference across the valve would
exceed a certain predetermined value--in this case the use of a
high pressure switch 42 may not be needed at all.
FIG. 2 shows a compressor 120, that again may be a screw or a
scroll compressor or any other compressor prone to an unpowered
reverse rotation. The further details shown by FIGS. 2 and 3 can be
utilized in either a screw compressor or the previously illustrated
scroll compressor. As shown, a valve 40 that functions as the prior
disclosed valve is mounted on a discharge line for the compressor
120. The compressor 120, as shown in FIG. 2, is a part of a heat
pump system having a four-way valve 122 that can selectively route
refrigerant either to an outdoor heat exchanger 48, or to an indoor
heat exchanger 52. Thus, the invention can be utilized in either a
cooling mode or in a heating mode.
FIG. 3 shows further possible features. In FIG. 3, the compressor
120 can again be either a scroll compressor or a screw compressor.
An economizer heat exchanger 202 provides an economizer function
and injection of a portion of the previously compressed refrigerant
back to an intermediate compressor chamber(s) of the compressor
120. The features shown in FIGS. 2 and 3 are generally known. It is
the incorporation of the valve 40, and the optional high pressure
switch 42 that is inventive.
Although a preferred embodiment of this invention has been
disclosed, a worker of ordinary skill in this art would recognize
that certain modifications would come within the scope of this
invention. For that reason, the following claims should be studied
to determine the true scope and content of this invention.
* * * * *